Process for producing zirconium alloys



Patented 7 Mar. 26, 1935 PROCESS FOR PRODUCING ZIRCONIUM ALLOYS Frederick M. Becket, New York, N. Y., assignor to Electro Metallurgical Company, a corporation of West Virginia No Drawing. Application 'May 16, 1934, Serial No. 725,900

3 Claims.

The invention is a process for producing zirconium alloys, and relates more especially to a continuous process for producing zirconium-sili-.

con alloys. Y

It is known that low-carbon zirconium-silicon alloys which contain at least as much silicon as zirconium may be produced in an electric furnace by reducing with carbon a mixture of zirconium ore and silica. It is also known that when the silica and zirconium are used in proportions to give an alloy containing more zirconium than silicon a substantial proportion of zirconium carbide is formed, and that this zirconium carbide builds up on the furnace hearth as a hard, dense, practically infusible mass which makes it impossible to tap the furnace. Hence, it has heretofore been commercially impracticable to produce by such a process alloys containing more zirconium than silicon, although there is a demand for ,such alloys.

I have now found that the hearth of zirconium carbide, formed as described 'above, may be decomposed and removed in the form of an alloy higher in silicon than in zirconium by operating the furnace with a relatively high ratio of silica to zirconium ore. This effect is quite surprising when the stability and refractory character of zirconium carbide are considered.

The process of the present invention comprises reducing with carbon in an electric furnace a mixture of silica and zirconium ore or compound in such proportions that an alloy containing more zirconium than silicon is produced, whereby a mass of zirconium carbide is gradually accumulated on the furnace bottom or hearth, continuing this step until the accumulation of zirconium carbide is sufficiently greatto interfere with the normal operation of the furnace; then reducing the ratio of zirconium ore to silica in the mixture charged to the furnace, whereby an alloy containing more silicon than zirconium is produced and the zirconium carbide on the hearth is gradually decomposed and removed, continuing this step until the mass of carbide is reduced to the desired extent; and then repeating the firstmentioned step. Thus, the invention is a continuous process which produces alternately alloys having a ratio of zirconium to silicon greater and less than one. I

60 As an example of the operation of the process of the invention, the following is typical. A furnace charge consisting of a mixture containing about:

was fed into an electric furnace continuously for several days. The zirconium ore used was a mixture of about equal parts of two ores having the following respective analyses: 7

The alloy produced during this stage of the process contained. more zirconium than silicon, and a typical analysis was:

. Percent Zirconium 54.73 Silicon 39.70 Iron 3.82 Aluminum plus Titanium 1.20 Carbon 0.25

After a period of several days the accumulation of zirconium carbide on the furnace hearth was so great that it was extremely diflicult to tap the furnace. Thereupon the furnace charge was changed to a mixture containing about:

The zirconium ore used was the same as in the previous stage. The alloy produced during this second stage contained more silicon than zirconium, and a typical composition was:

- Per cent Zirconium 38.17 Silicon 51.29 Iron 8.26 Titanium 0.59 Carbon 0.26 Aluminum 0.55

After the furnace had been operated several days on this second stage, the zirconium carbide accumulated had been removed sufliciently, and the ratio of zirconium ore to silica in the charge was again raised to produce the higher zirconium alloy.

When it is desired to remove the zirconium carbide hearth rapidly, the furnace may be run with a charge containing no zirconium ore. Under these conditions the hearth supplies all-of the zirconium in the alloy so produced.

All proportions herein are by weight.

I claim:

1. The process of producing zirconium alloys which comprises reducing with carbon in an electric furnace a mixture of silica and zirconium ore or compound in proportions to produce a zirconium-silicon alloy containing more zirconium than silicon, whereby zirconium carbide is accumulated in the furnace, and subsequently operating the same furnace with a charge containing silica and which yields in the presence of the said zirconium carbide a zirconium-silicon alloycontaining more silicon than zirconium, whereby the said zirconium carbide is decomposed and removed from the furnace;

2. The process of producing zirconium alloys which comprises reducing with carbon in an electric furnace a mixture of silica and zirconium ore or compound in proportions to produce a zirconium-silicon alloy containing more zirconium than silicon, whereby zirconium carbide is accu- -mulated in the furnace, and subsequently reducing with carbon in the same furnace a mixture of silica and zirconium ore or compound in proportions to produce a zirconium-silicon alloy containing more silicon than zirconium, whereby the said zirconium carbide is decomposed and removed from the furnace.

3. The continuous process of producing zirconium alloys which comprises reducing with carbon in an electric furnace a'mixture of silica and zirconium ore or compound in proportions to produce a zirconium-silicon alloy containing more zirconium than silicon, whereby zirconium carbide is accumulated in the furnace, and subsequently sufficiently increasing the ratio of silica to zirconium ore in said mixture to produce a zirconium-silicon alloy containing more silicon than zirconium, whereby the said zirconium carbide is decomposed and removed from the furnace; and repeating this procedure in continuous fashion.

FREDERICK M. BECKET. 

